The fifth-generation (5G) mobile telecom network has been a focal point of research amongst the community in recent times. New threats have also emerged. Security metrics provide a pathway to quantitatively measure the security posture of an environment. We need to analyze if and how existing security metrics can be applied to a 5G environment. This thesis aims to do a state-of-the-art survey to explore the diverse set of security metrics in literature, understand the process of deriving security metrics. With this knowledge, we investigate the factors that hinder the usage of existing security metrics in a 5G environment, identify solutions from existing literature on how to address those factors, propose an adapted security metrics approach to address the multi-ownership nature of 5G, and discuss the design and analysis of Argus-5, a tool designed to verify the feasibility of the adapted security metrics approach and simulate various scenarios.